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/*
* Copyright (C) 1998, 2000-2007, 2010, 2011, 2012, 2013 SINTEF ICT,
* Applied Mathematics, Norway.
*
* Contact information: E-mail: tor.dokken@sintef.no
* SINTEF ICT, Department of Applied Mathematics,
* P.O. Box 124 Blindern,
* 0314 Oslo, Norway.
*
* This file is part of SISL.
*
* SISL is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as
* published by the Free Software Foundation, either version 3 of the
* License, or (at your option) any later version.
*
* SISL is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public
* License along with SISL. If not, see
* <http://www.gnu.org/licenses/>.
*
* In accordance with Section 7(b) of the GNU Affero General Public
* License, a covered work must retain the producer line in every data
* file that is created or manipulated using SISL.
*
* Other Usage
* You can be released from the requirements of the license by purchasing
* a commercial license. Buying such a license is mandatory as soon as you
* develop commercial activities involving the SISL library without
* disclosing the source code of your own applications.
*
* This file may be used in accordance with the terms contained in a
* written agreement between you and SINTEF ICT.
*/
#include "sisl-copyright.h"
/*
*
* $Id: sh6idfcros.c,v 1.1 1994-04-21 12:10:42 boh Exp $
*
*/
#define SH6IDFCROSS
#include "sislP.h"
#if defined(SISLNEEDPROTOTYPES)
void
sh6idfcross(SISLIntdat *pintdat, SISLIntpt *vcross[], int *jncross,
int ipar1, int ipar2, int *jstat)
#else
void sh6idfcross(pintdat, vcross, jncross, ipar1, ipar2, jstat)
SISLIntdat *pintdat;
SISLIntpt *vcross[];
int *jncross;
int ipar1;
int ipar2;
int *jstat;
#endif
/*
*********************************************************************
*
*********************************************************************
*
* PURPOSE : Given intersection data. Check if there exist 4
* intersection points where where the parameters
* corresponding to each object in the intersection
* are pairwise equal.
*
*
* INPUT : pintdat - Intersection data.
* vcross - Intersection points found so far.
* jncross - Number of intersection points found so far.
* ipar1 - Number of parameter directions of first object.
* ipar2 - Number of parameter directions of second object.
*
* OUTPUT : vcross - Intersection points found.
* jncross - Number of intersection points found.
* jstat - Status
* jstat = 0 => No set of points is found.
* jstat = 1 => Successful. 4 points are found.
*
*
* METHOD :
*
*
* REFERENCES :
*
*
* CALLS : s6dist - Distance between points.
*
*
* WRITTEN BY : Vibeke Skytt, SI, 12.92.
*
*********************************************************************
*/
{
int ki,kj; /* Counters. */
int kpt; /* Index of last intersection point found. */
int kpar1; /* Start index of current parameter set. */
int kpar2; /* Number of parameter in current set. */
double tdist; /* Distance between parameter points. */
SISLIntpt *pt; /* Current intersection point. */
SISLIntpt *qnext; /* Next point to find. */
/* Test if there is 4 points in pintdat. */
if (pintdat->ipoint < 4)
{
/* No possibility of cross intersections. */
*jstat = 0;
return;
}
/* Test if a set of cross intersections is found. */
if (*jncross == 4)
{
/* Test if the second parameter set of the last intersection point
found is equal to that of the first point. */
tdist = s6dist(vcross[0]->epar+ipar1,vcross[3]->epar+ipar1,ipar2);
if (DEQUAL(tdist+(double)1.0,(double)1.0))
/* The set of points is found. */
*jstat = 1;
else
*jstat = 0;
return;
}
/* Prepare for a search for the next point in the set. */
kpt = (*jncross) - 1;
pt = vcross[kpt];
kpar1 = (kpt % 2 == 0) ? 0 : ipar1;
kpar2 = (kpt % 2 == 0) ? ipar1 : ipar2;
/* Traverse the intersection points to find a point that has got
one parameter set equal to the current one. */
for (ki=0; ki<pintdat->ipoint; ki++)
{
qnext = pintdat->vpoint[ki];
/* Check if the point is found already. */
for (kj=0; kj<=kpt; kj++)
if (qnext == vcross[kj]) break;
if (kj <= kpt) continue;
/* Check if the next point belongs to the wanted set. */
tdist = s6dist(qnext->epar+kpar1,pt->epar+kpar1,kpar2);
if (DEQUAL(tdist+(double)1.0,(double)1.0))
{
/* A point is found. */
kpt++;
vcross[kpt] = qnext;
(*jncross)++;
/* Find next point. */
sh6idfcross(pintdat,vcross,jncross,ipar1,ipar2,jstat);
if (*jstat == 1) return; /* The entire set is found. */
(*jncross)--;
kpt--;
}
}
/* No set of cross intersections exist. */
*jstat = 0;
return;
}
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